1. Field of the Invention
The method and apparatus of the invention relate generally to the field of measuring and/or interacting with relationships between or among a plurality of media and/or spatial materials, by way of example, to the measurement of quantity of fluid in a container. Sensors which garner naturally inherent, virtual and/or artificially generated frequency/energy emissions are directed toward each media of interest in a constellation of relatively proximate objects. Emitters of focused or non-focused, collimated or non collimated, pulsed or continuous beams of electromagnetic energy may be aimed or directed at one or more of such media and the resultant reflections or returns captured by the same or different sensors. The data and/or images thus obtained can be monitored, verified, processed, manipulated, stored, displayed, communicated and reproduced as desired or required.
2. Related Background Art
The advent of the modem computer has greatly enhanced the fields of absolute and relative measurement and increased the speed at which spatial, geometric and temporal relationships, whether natural, virtual or artificial, may be calculated. Display technology now permits large scale visual reproduction of data and images representing multi-dimensional relative proximity. However, current art does not provide useful, often badly needed, sometimes critical information.
For instance, oil companies may not be cognizant of leaks in storage facilities until serious environmental damage has already occurred. The leak may be so slow from a storage tank in terms of fluid loss over time that the leak is not detectable through available monitoring techniques. Most devices for measuring the contents of containers are incapable of accurately measuring the quantity of material inside the structure. If sufficiently accurate means is provided by the application of currently available technology, then costs may become prohibitive for providing such means. Transport, storage and other functional housings of materials produced by the oil and gas industry are presented here as prime examples of devices where the relationship of cost to accuracy of measurement may contribute to an undesirable and otherwise untenable definition of politically and socially acceptable, albeit, dangerous risks. Anyone experienced in the oil and gas industry knows that a used petroleum storage tank is never really safe. In fact, the incidence of welding accidents and maintenance personnel deaths when such tanks are inspected, cleaned or otherwise maintained are numerous. Even when so-called nitrogen "blankets" are applied to such tanks to prevent accidents from occurring, the accidents can and do occur. Equally devastating, as indicated above, are the environmentally damaging petroleum spills and leaks which are not detected until too late by current methods of content(s) monitoring.
U.S. Pat. No. 5,493,903 describes the application of a strain gauge sensor to the exterior wall of a tank. The greater the volume of a substance within the tank, the greater the force pushing on the tank walls. The greater the force pushing on the tank walls, the greater the deformation of the walls which is translated into a strain gauge reading. An exterior storage tank, however, is not subjected to uniform temperatures and pressures due to weather conditions and the like which can alter the readings over time of day and season. While simple, the solution is not particularly accurate nor does it solve the problem of measuring the contents of underground or otherwise enclosed storage facilities.
Similarly, U.S. Pat. No. 5,487,300 describes the use of a pressure sensor connected to the opening of a tank for indicating the pressure of the liquid in the tank. A processor translates the pressure signal to a level signal. There may, however, be sludge or other measurement distorting material at the opening of the tank where the pressure sensor is located that can clog the opening and distort or interfere with the accuracy of the level reading.
Other known techniques for level detection include using a manual dip stick. However, the use of a dip stick requires that the stick be inserted perpendicularly to the bottom of the container. If the stick is inserted at an angle, the reading will be artificially high. Of course, use of a dip stick is not automatic in that it requires a person's presence to take the reading. Moreover, the person taking the reading, depending on the contents of the container, may have to wear a gas mask or other safety apparatus to prevent inhaling dangerous fumes.
Still other efforts to measure container contents have focused on the use of "pulse radar level measurement" such as various products produced by the Ohmart Corporation of Cincinnati, Ohio. However, such devices are less accurate, generally more expensive and pose difficult installation problems. Further, they lack many features of the current invention including off-site interactive telemetric communication and control.
U.S. Pat. No. 4,774,403 describes a position measuring device using a triangulation scheme for position sensing. According to the invention, a laser light beam is reflected off the surface of container contents differently from when light is reflected off the bottom surface of the container. A lens of a sensor deflects the received light to different locations of a CCD linear array. Also, U.S. Pat. No. 5,337,289 discloses an acoustic surface mapping system useful in mapping the contours of solid container contents.
Current methods do not delineate between the petroleum and water content, particularly in lease storage tanks and even in the tanks located at refineries. Nor do they give early warning of the theft of petroleum products from tanks, many of which are in remote locations. This is particularly problematic in underdeveloped countries where the additional hazard of intentional sabotage may greatly increase the incidence of severe environmental damage and product loss and where many industrialized nations now expend a large portion of their exploration and production budgets. Consequently, it is clear from the prior art that there exists a need for an improved means of acquiring container content information and promptly responding to such information via telemetric directives or other means available in various embodiments of the current invention to avoid the severe consequences that may result from having inaccurate or unreliable measurements.